1. Field of the Invention
The present invention is directed to a system for and method of deriving subsoil structure data and, more particularly, to a system for and method of obtaining data to produce at least a two dimensional plot of subsoil structure, of relatively high resolution.
2. Description of the Prior Art
Knowledge of the subsoil structure or stratigraphy, surrounding an existing borehole, even a dry hole, is useful in the selection of potential sites for oil well drilling. Knowledge of the stratigraphy is also useful in assessing potential reserves, and thereby aid in planning continued development of an oil field. Such knowledge would increase significantly if one were to have a multidimensional plot or graph of the subsoil structure, with sufficiently high resolution, capable of displaying the relative locations of both small and large structures and layers.
Herebefore, with prior art techniques only limited knowledge has been obtained of the subsoil structure. For example, information developed from logs and cores boreholes provides only localized data in the immediate vicinity of the holes. Only limited data is obtained from conventional seismic reflection measurements, made at the surface, since in many land areas it is difficult to determine the proper static corrections. Also, the weathered top layer near the surface greatly attenuates high frequency returns, particularly due to the two-way passage of the transmitted signals and reflected returns through the weathered layer. This impairs the resolution of data relating to deep features.